I’m not saying it’s wrong that PK and BD are racially different.
It is neither wrong nor untrue.
But there is some degree of overlap in some individuals.
Proportionally I agree the vast majority are different.
But not all.
Case in point although it is largely anecdotal.
I myself come from a family where my paternal grandmother was from a Persian background however was born in West Bengal.
Maternally, I am not sure where my grandparents came from other than East Bengal, but my grand mother was extremely fair skinned.
As for me, I look more Pakistani than some Pakistanis.
That’s just me.
There are many other Bengali’s (mostly girls) that I know who you really couldn’t tell if they are Indian, Pakistani or Bangladeshi.
Again anecdotal.
But the point I’m making is that there is overlap and mixing of various ethnicities in various degrees all over South Asia.