Vol. 8, No. 4, 2002 Page 4
A number of years ago, psychologist Jay Belsky proposed an explanation for the finding that girls whose fathers abandon them tend to reach puberty early, and to exhibit increased promiscuity. Belsky suggested that girls exposed to high levels of stress, particularly due to paternal absence in early childhood, may often respond by becoming depressed and insecure, gaining weight and then experiencing accelerated puberty as a result of hormonal changes precipitated by the weight gain, and becoming sexually active with multiple partners and unstable relationships often resulting in early childbearing.
New research, however, suggests a more straightforward biological explanation for the link between paternal absence and both early puberty and promiscuity in girls. David Comings and colleagues tested 121 men and 164 women (not related to the men) for the presence of different variants of the X-linked androgen receptor (AR) gene. A "short" variant of the gene is believed to lead to enhanced androgen activity. (Androgens are steroid hormones that affect male sexual and behavioral characteristics, but also are present in women.) Comings et al. have previously shown an association between the shorter variants of the AR gene and attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder.
The new study found that in male subjects, the shorter AR allele was associated with assaultive behavior, impulsiveness, sexual compulsiveness and increased number of sexual partners, and feelings of reduced internal control. In females, the presence of two copies of the short AR variant was associated with parental divorce, paternal absence during childhood, and early puberty.
The researchers say their data suggest a likely explanation for the link between paternal abandonment and early puberty in girls: "The behaviors in the fathers, manifested by marital conflict and abandonment, and in the daughters, manifested by early onset of puberty (precocious sexual activity, early age of childbearing, and disruptive personal relationships) are due to shared genes passed from the fathers to their daughters." They note that the involvement of an X-linked gene, passed on from fathers to daughters but not to sons (who inherit a Y chromosome from their fathers), could explain why paternal absence has a smaller effect on boys than on girls.
In addition, they say, their findings could explain why girls whose fathers die do not experience the same changes in behavior and timing of puberty onset as girls whose fathers abandon them (since the fathers who die early would be no more likely to carry the short AR gene variant than would fathers in the general population). A genetic explanation also is consistent, they note, with the strong correlation between the age of puberty onset in mothers and their daughters.
Comings et al. caution, however, that their study is preliminary and that their theory needs to be further tested by comparing "absentee" fathers and their daughters to intact father-daughter pairs.
"Parent-daughter transmission of the androgen receptor gene as an explanation of the effect of father absence on age of menarche," D. E. Comings, D. Muhleman, J. P. Johnson, and J. P. MacMurray, Child Development, Vol. 73, No. 4, July-August 2002, 1046-51. Address: David E. Comings, Department of Medical Genetics, City of Hope Medical Center, Duarte, CA 91010, dcomings@earthlink.net.