To deliberately deny a child the right to know its mother is not altruism, it’s evil.
Can I just ask why it is not evil for a same sex female couple to use an anonymous sperm donor and 'deny their child the right to know its father'? Why is it so different when it is a mother? Is it based on the myth that all mothers are caring and nurturing (which we as feminists know is largely socially constructed to keep women in the private sphere)?
If it's evil to deprive a child of a mum, it's evil to deprive it of a dad, meaning that female couples can't have IVF.
In my view, the true parent is the one raising the child. If people didn't fixate hugely on biological connections, the focus would be on the caring relationship, which is the important one for the child. I don't understand the emphasis on blood ties- the law will sometimes prioritise someone who you hate but share DNA with over someone who you care about deeply but have no legal or biological relationship with.
I also think part of the reason children who are adopted sometimes feel psychologically conflicted is because society makes such a big deal out of the idea of 'real mum' and 'real dad' and seems to imply that only biological mothers can give real maternal love.