You should check what a 12 year old looks like, they look like 6 to me. A 16 year old looks way more mature cause hormones already hit them, that's why in movies/series they pick people about 20 to play teens but children to play 12 year old children. Also 16 year old teens put their eyes on kids their own age and mostly higher, if they find a 12 year old that looks literally like a child beautiful they should check themselves. Honestly, just look at a picture of yourself at 12 and then 16, the change is insane, hormones are scary cause 4 years is not too much, but the difference in the body is insane and it makes this not okay.
Well , I think my comment really sounds wrong... I know that pdf is NOT about age difference but rather attraction to prepubescent kids... in that 12 years old and 16 years old getting married sounds really wrong cuz 12 yr old is literally a kid ... but I am saying that maybe the romance will start later after they are grown up ...

These BL writers are hiding their PDF tendencies by making the child the top and the older guy bottom. They're like "how do I make it acceptable for a 16 year old teen to fall for a 12 year old kid without sounding like a PDF? I know, let me make the child become the top".
An age gap it's only okay if they're both adults, why are so many BLs getting children involved lately? It's sick