I think baby birds imprint on whatever they see first that moves when they hatch. What they imprint on is what they try to stay close to during their early stage of growth. I would say their tendency to imprint is probably genetic, but what specifically they imprint on is not.
Could it be similar for humans? I remember as far back as age 2 and a half. I remember the feeling of the scarf Mom put on my head when I went outside and loving the feminine feel of it. I remember around age 4 asking Mom if I would be like her (a woman) when I grow up. I enjoyed activities with Dad in those early years, but Mom's traits appealed to me much more. I think I was probably called pretty at that time and I think I felt pretty. I wanted to be pretty like Mom when I grew up.
Do you think you may have "imprinted" on your Mom when you were very young? Did you like your Mom more than your Dad? Do you think you may have wanted to be like her at an early age? Does it seem very probable that your desire for femininity started in that way?