Hipocresy in sex equality

In Mass effect 3 Liara has a father who is a female
Due to her alien species being all phisicaly females
And has a mum
That's how it should be
Father , person who inpregnates
Mother , person that gets pregnant
Like if a kid has "two mums" or "two dads"  (homosexual parents) one should be the dad and one the mum , no matter if their are male or female
Being male or female should be irrelevant to it .
People that question families of two females and a kid/ two males and a kid , are clearly saying they think this makes a bad difference.
Not just as homosexuals individuals but as males and females.
Why does a family need a female and a male ? Aren't women capable of doing the same things as men ?Aren't women capable of doing the same things as male parents ?
I see no difference.
Two females or two males or one male and one female