Hi ,

This idea came in my mind and I realized I don't have an answer for it . Maybe it is simple but anyway I will ask :

How is it that when identic twins are conceived , if they will be boy and girl ,the girl's brain will be altered by estrogen and the boy's brain will be masculinized by testosterone . I am not sure , but I thought they would share everything (like blood , including hormones : type and concentration ) inside their mom .

They're not identical if they are physically male and female...and what causes a TS condition is some extraordinary circumstances re: mother's hormones...under normal conditions, a fetus will develop mentally inline with its body.

If they are identical (one to be cis-female and the other to be MtF, for example), it may be that the growth and development rates will not be 100% exactly alike time-wise, which creates the "window of opportunity" for a TS condition to exist in one twin, but not the other.

Thanks