My deceased younger gay brother got the most of the *wrong* attention from our mother. I don’t know if he was born gay, but the reality is he never had a chance of being a normal hetero. My older brother and I somehow escaped most of the weird sh1t and only had to deal with the emotional violence, alcoholism and bipolar stuff.
Either way, I credit my mother with much of his psychological problems.
No one is born gay, it’s a choice. It may be that his choice was pushed upon him by your mother, but he wasn’t born gay.