Except the British didn't genocide during the partition of India - the internal clash of Sikhs, Hindus, and Muslims going to war was it's own doing... You're framing it like British soldiers went in there and massacred India during that time. Wrong.
Ultimately self determination involves taking responsibility.
You may not even disagree; you and GP state different things which may both be true depending on what is understood by "fault"
"It's more complicated than tha..."
No, it's not.