Young Seymour: No! Mother, no! I don't want you to become a fayth!
Seymour's Mother: There is no other way. Use me and defeat Sin. Only then will the people accept you.

This flashback was seen in Zanarkand along with a flashback of another High Smmoner named Yocun and of course the ones with Braska, Jecht and Auron.

Consider also that when Yunalesca lists the bonds strong enough to make a Final Aeon capable of defeating Sin, she lists the bond between mother and child.

Anima was clearly made by Yunalesca and it was intended to defeat Sin.