How many mum do you have?

I just received some spam that suggested that I should shop early for my "No 1 Mom". Now I appreciate that in these days of multiple marriages and relationships it is quite possible to have a number of women who have had "mom or mum" in their titles. But only one of them will be your birth mother (or adopted mother if that is your circumstance). That doesn't necessarily make her your favourite Mom/Mum of course. Who is your No 1 Mom/Mum - your birth mother or someone else?