Given that porn canโt sexualize anyone under 18, she would have had to be at least 18 when she conceived her first child.
Since MILFs in porn are generally โmy friendโs momโ or something generationally similar, ie the MILF is defined as such by someone the age of her child, said child and their peers must be at least 18 as well.
Therefore, the minimum age for a MILF character in a porn, legally and mathematically, should be 36
If the kids make an appearance in the porno, they would have to be 18+. He does specifically point out porno milfs. Although I suppose the kids could just be implied in the event of a porn.