Behavior Genetics: What's New? What's Next?

What's new in behavior genetics? With widespread acceptance that nearly all behavioral variation reflects some genetic influence, current studies are investigating developmental changes in the nature and magnitude of genetic and environmental effects, the extent to which different behaviors are influenced by common genes, and different forms of gene-environment correlation and interaction. New designs, focused on assessment of unrelated children in the same households or neighborhood environments, and use of measured environmental variables within genetically informative designs, are yielding more incisive evidence of common environmental effects on behavior. What will be next? Behavior genetic techniques and analyses will be used to inform efforts to find genes altering susceptibility for disorder and dispositional genes affecting behavioral variation. The developing integration of behavioral and molecular genetics will identify genes influencing specific behavioral variation and enhance understanding of how they do so. Psychologists will play a pivotal role in communicating that understanding to the public and in facilitating consideration of the inevitable ethical issues then to be confronted.     

Y haplogroups and aggressive behavior in a Pakistani ethnic group

Studies show that personality dimensions such as aggression are influenced by genetic factors and that allelic variants located on the Y chromosome influence such behavior. We investigated polymorphisms on the male-specific region of the human Y chromosome in 156 unrelated males from the same ethnic background, who were administered the Punjabi translation of the Buss and Perry Aggression Questionnaire that measures four aspects that constitute aggressive behavior, i.e. physical aggression, verbal aggression, anger, and hostility. A value of .85 for Cronbach's coefficient alpha indicates considerable internal consistency and suggests that the psychometric properties of the aggression questionnaire can be adapted for the Pakistani population. A mean score+/-SD of 69.70+/-19.95 was obtained for the questionnaire. Each individual was genotyped following a phylogenetic hierarchical approach to define evolutionary Y haplogroups. Five Y haplogroups that are commonly found in Eurasia and Pakistan comprised 87% (n=136) of the population sample, with one haplogroup, R1a1, constituting 55% of the sampled population. A comparison of the total and four subscale mean scores across the five common Y haplogroups that were present at a frequency > or =3% in this ethnic group revealed no overall significant differences. However, effect-size comparisons allowed us to detect an association of the haplogroups R2 (Cohen's d statistic=.448-.732) and R1a1 (d=.107-.448) with lower self-reported aggression mean scores in this population.     

Opportunity recognition and the tendency to be an entrepreneur: A bivariate genetics perspective

We applied quantitative genetics techniques to a sample of 851 pairs of monozygotic and 855 pairs of dizygotic female twins to examine the influence of genetic factors on the variation across people in opportunity recognition. We also examined the extent to which the same genetic factors contribute to both opportunity recognition and the tendency to be an entrepreneur. We found substantial heritability for opportunity recognition (0.45), with no influence of the shared environment. Moreover, we found that 53% of the phenotypic correlation between opportunity recognition and the tendency to be an entrepreneur had a common genetic aetiology.     

Agonistic behavior and social reactivity of LG/J mice in both an arena and a seminatural setting

In order to determine the relatively long-term effects of having been primed for agonistic behaviors in an arena setting, 28 male LG/J mice were observed for these behaviors in a seminatural environment for a period of 5 days following a 20 min arena test. The mice were first placed in an arena in which they were allowed either immediate physical contact with another strain (control condition) or were briefly separated from another strain by a transparent partition before being allowed physical access to them (priming condition). Subjects, recorded as either having fought or not fought in the arena, were then placed in a 101 cm square seminatural setting. Seven trials, using 8 LGs each (4 arenaexperienced males and 4 naive females), were made, and agonistic behaviors were recorded for the priming and control condition subjects. The results showed that the control condition fighters (CF) like the priming condition fighters (PF) fought in the arena situation, but different agonistic patterns in the seminatural setting were noted. While in the seminatural environment, both CF and PF mice were attacked frequently and submitted frequently, but PF mice attacked opponents more frequently than did CF subjects (p < 0.025) and elicited significantly more submissions from opponent mice than did CF mice (p < 0.025). It is concluded that: (1) there are more and different agonistic behavior patterns available in the more natural environment than in the arena setting, and more specifically (2) there is a greater effect on agonistic behaviors in a seminatural environment for mice that fought when exposed to the arena priming procedure as compared with mice having fought in the arena control condition.     

Predatory aggression in lines of wild mice selected for interfemale aggression

Mice descending from lines previously selected for high and low levels of interfemale aggression and from a nonselected control line were exposed to live crickets on two consecutive test days. Latencies both to attack and to eat the cricket were recorded. No line or sex differences in attacking were found, although latency to attack decreased over test days. Control line mice were more likely to engage in the eating of the cricket than either the high or low selected lines, suggesting that the selection procedure may have dissociated attacking and eating components of predatory behavior.     

A Prophetic Seer Potentiating Us in the Present

In his book Radical Evolution Joel Garreau functions as a prophet and a seer. In presenting a narrative of the future that includes an optimistic view of human nature, he warns that because of the GRIN technologies (genetics, robotics, information technology, and nanotechnology) the quickening evolution of “The Curve” is upon us and could well soon culminate in the mind-boggling social change of “The Singularity.” Garreau considers three scenarios of the technological future: the Heaven Scenario, the Hell Scenario, and the Prevail Scenario. The third wins favor because the heavenly envisionment with its evolution of a superintelligent human who could engineer a species with a greatly extended lifespan is too blissful and the hellish prognostication with its destruction of the human species within the next quarter century is too pernicious. Just right is the middle-of-the-road perspective of the Prevail-Transcend depiction of the future. This third view is indeed more appropriate than the first two scenarios, but a more nuanced form of the third perspective—emphasizing similarly the role of human freedom and responsibility in continuing to reshape human nature but drinking less deeply of the transhumanist elixir and more deeply of a pantransentheistic potion—would constitute a more suitable vision of the future.     

Approaching Religious Guidelines for Chimera Policymaking

Recent developments in the use of cow egg cells to clone human somatic cells, and the grafting by researchers at several universities of human neurons into mice, bring the notion of the chimera, a mixture of several living organisms, from myth into reality. In his article “Cross‐Species Chimeras: Exploring a Possible Christian Perspective,” Neville Cobbe considers the religious arguments overlying the creation of human‐nonhuman chimeras. In my commentary I focus on the distinction between germline‐ and tissue transplant‐related chimeric techniques implicit in Cobbe's essay and argue that the former poses more serious moral difficulties than the latter if the chimeric product is brought to term. The substantive view of the imago Dei, or image of God, serves as a scaffold by which to judge the permissibility of chimera creation using stem cell and other tissue implants. While useful for judging the rights of such artificially generated beings, I argue that specific criteria such as proportion of tissue uptake, mental capacity, and adherence with the organism's telos are more appropriately considered within a composite image of the living being reflecting its unique integrality. Human co‐creativity with the Divine will inevitably prompt attempts to generate medically useful chimeras. Religious dialogue, combined with the categories of religious moral argument appearing in Cobbe's essay, will help to establish the outline of feasible policy guidelines addressing the complexities inherent in the creation of chimeras.     

The heritability of antisocial behavior: A meta-analysis of twin and adoption studies

In this paper, we describe a quantitative summary of 12 twin (n=3795 twin pairs and 3 adoption studies=338 adoptees) published since 1975 which provided 21 estimates of the heritability of antisocial behavior. Medium to large effect sizes were found for genetic influences across studies, with approximately 50% of the variance in measures of antisocial behavior attributable to genetic effects. Although effect sizes did not vary across different definitions of antisocial behavior (criminality, aggression, or antisocial personality), significantly larger estimates of genetic effect were found for severe manifestations of antisocial behavior. The importance of severity was further underscored by the significantly larger effects obtained in studies using clinic-referred samples compared to the effects obtained in studies using volunteer samples. Demographic characteristics of the samples did not influence effect sizes, although studies using more stringent methodology tended to find larger effects. These results must be interpreted in light of the small literature that was suitable for the meta-analysis due to numerous methodological limitations in existing studies.     

Complexities in Cancer Risk Counseling: Presentation of Three Cases

Complexities abound in the identification and management of families at increased risk for inherited forms of cancer. One of the ways to learn as a profession how best to provide cancer risk counseling (CRC) is to share counseling experiences. Such cases can provide insight into the issues raised by families and ways in which genetic counselors have handled complex situations. Here we describe three CRC cases initially presented at the 1995 American College of Medical Genetics meeting. The first case involves balancing the importance of informing a family of the presence of an inherited cancer syndrome with the family's right not to know. The second case illustrates the difficulties in assisting an individual to make medical management decisions in the face of uncertain risk information. The third case describes the complex interactions with a woman before and after her decision to have prophylactic surgery. (affiliated with Long Beach Memorial Breast Center at the time of counseling)