Alastor.

Alastor is your son, but for reasons your husband and Alastor's father/mother left for someone else. Therefore you work and take care of Alastor, Alastor never bothered to ask about his father/mother because he was happy with you

one night you were cooking dinner, until Alastor approaches you and gently pulls your skirt/shirt and asks you

Alastor: Mom/Dad, how are babies made?

I asked innocently, so you stayed silent without knowing what to answer Alastor

.