Bad logic, Kashmiri and Tamil people (both Indian) are 1000s of km apart, so are Bengali and Pashtun people. I am asking how are people who live in Lahore so different from people living in Amritsar/Jaipur or Jammu/Srinagar. Also, mass migration did the opposite of what you are saying, a bunch of our Muslims went to Pakistan, while all your Hindus and Sikhs and non-Muslims came to India. If anything, the 1947 migration mixed India and Pakistan more ethincally/genetically.
Secondly, I find it funny personally as a person who had some ancestors in present day Pakistan how you guys love to pick on people like Tamils/Bengalis/etc. Your real fight was with us during Partition (non-Muslim Pakistanis from Punjab/Sindh/rest of Pakistan and northern India). The so called Tamils and Bengalis in India couldnt care about Pakistan, because they have never interacted with you. You keep trying to malign the wrong people, just saying.
They are different because they are different religions.
Its like asking why to Parsis look different than Hindus but even though they both live in Bombay.
When Islam came to the Sub-continet, it was brought by Arabs, Persians who then settled in these areas and inter-married with the local population creating a unique mix among the muslim population.
In a similar way the Spanish Conquistadors colonized Latin America and inter-married with the local population.
So there are some Mexicans who look totally European, some partially, some completely indigenous.
Now add a layer of religion on top of this. Lets say the totally European looking or partial ones are the ones who converted to Christianity while the Indigenous did not.
And lets say those Christians want their own country and there mass movement of people.
Now the new country of Christians will have a radically different population than the Indigenous one.
Same applies to Pakistan and India.
The Muslims in India were a product of inter-marriage between Arabs/Turks/Persians and the native Indian population and when the countres split apart, they migrated to the new country and thus you have large differences between Indian and Pakistanis.
I have been living in bay area (silicon valley) from last 7 years. I have yet to meet a pakistani who is software engineer.
Hello.
There you have met me. I am a Software engineer