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There has always been some speculation that immunology plays a role in sexual traits given the fraternal birth order effect (i.e. a son is more likely to be hom

• appleflaxen 8y ago
  why would the presence of a fraternal birth order effect mean that it's immunological?
  • todd8 8y ago
    I assume that it would be the mother’s immune system (sensitized by previous pregnancies) response affecting the fetus while in utero.
  • dooglius 8y ago
    The paper explains, According to this maternal immune hypothesis, cells (or cell fragments) from male fetuses enter the maternal circulation during childbirth or perhaps earlier in pregnancy. These cells include substances that occur only on the surfaces of male cells, primarily male brain cells. The mother’s immune system recognizes these male-specific molecules as foreign and produces antibodies to them. When the mother later becomes pregnant with another male fetus, her antibodies cross the placental barrier and enter the fetal brain. Once in the brain, these antibodies bind to male-specific molecules on the surface of neurons. This prevents these neurons from‘‘wiring-up’’in the male-typical pattern, so that the individual will later be attracted to men rather than women.
  • danieltillett 8y ago
    It doesn't, but apart from this study the mothers's body is somehow able to remember how many sons she has had and influence the sexuality of her later sons. This memory of past exposure to a foreign object (i.e. a foetus) is the hallmark of immunology.