A good summary of why the 'I have a PhD in science' gamete argument is redundant:
rosieswayne.blogspot.com/?m=1
'...I don’t know what it’s like to be trans, but I do have the relatable experience of having something integral to my life called into question “because biology”.
My adopted son is my son. I know it, he knows it, it is an unshakable truth to us. Yes, it is possible for a child to have two mothers. No, this is not because I ‘identify’ as being the actual person who gave birth to him and/or believe the sperm was conjured up with pure lesbian enthusiasm. But our children have two mothers and we have two sons - this is a reality, and we expect the same legal protection and respect as any other family.
However, if we apply “because biology” to my family (and there are plenty who are keen to), it isn’t actually a family at all - we’re just a couple of single mothers with bastard only children in an unusually cosy house-share situation.
Luckily for us, we live in a time and place where the law actively protects our family from this wilfully ham-fisted interpretation of how biology relates to actual human people. It is not something we take for granted.'