You are probably aware that babies in the womb before birth are vulnerable to all sorts of harm if the mother does not take good care of her health. The process of growing a person in the womb involves probably trillions of complex biochemical processes, many of which are vulnerable to outside interference. If the mother drinks alcohol, takes some prescription medications, experiences extremes of physical or emotional stress, depression, becomes ill, etc., the developing baby in her womb can be affected in all sorts of complex ways, and even severely harmed.
In the 1950s a sedative drug named Thalidomide was introduced to reduce the effects of morning sickness for pregnant mothers. It was subsequently found to have caused terrible birth defects in some of the resulting babies.
In a similar way, fetal alcohol syndrome is characterized by a wide ranging set of symptoms experienced by babies born to mothers who drink alcohol during pregnancy. Depending on when during the pregnancy the mother consumes alcohol, all sorts of complex harm can be caused to the baby, especially in brain development where entire brain structures may fail to develop or develop abnormally. These symptoms can affect these people throughout their lives. While we know some of the ways that babies can be affected by outside events during pregnancy, there is a great deal more that we do not know, because the development of a person from a sperm and egg is a staggeringly complex process about which we actually know comparatively little.
I have known someone closely whose mother was a severe alcoholic, and when I read the article at the link below I immediately recognized nearly every issue described in this article, albeit in an adult form. As an adult, FAS victims develop a variety of coping skills and may live what appears to others as a reasonably normal life, with the full implications only visible to those who are very close.
Please read the following document for more details:
Studying FAS led me to understand more clearly an important distinction in the "Nature vs Nurture" debate. Many have written about this as if TS must either be genetically transmitted, or learned behavior, or some combination. Understanding the fragility of brain development, and understanding that every thought and feeling we hold has it's locus in the brain, either as patterns of firing (which can represent short term memory or "learned behavior"), or as neural pathways (which can be long term memory), but also as core, critical, differentiated structures of the brain which in some cases are irreplaceable. If the Corpus Callosum for example is not developed in-utero I don't believe it can develop later. If - as increasing evidence suggests - there are diffentiated brain structures associated with our core gender identity, then the development of these structures can be interfered with in-utero just like other structures.
For a host of reasons, it is my belief that this is the most reasonable explanation for TS, and probably other sex and gender related variations we see. This would explain the profound resistance to so-called "cures" from various "therapies." It could also explain the tremendous pattern of common themes in so many different TS from widely divergent backgrounds with or without any known family history of TS to suggest a genetic link. It could also explain the incredible resilience of TS feelings across decades of experience, and that many have experienced waves of recurring dysphoric pressure even after years of avoidance and work to repress the feelings.
For me, this understanding was the beginning of my ability to accept and even "forgive myself" and let go of the self-loathing that I had learned from the ever-present cultural feedback. I hope it may serve as food for thought for some others.