"Section 56(2)(vi) : where any sum of money, the aggregate value of which exceeds fifty thousand rupees, is received without consideration, by an individual or a Hindu undivided family, in any previous year from any person or persons on or after the 1st day of April, 2006, the whole of the aggregate value of such sum
Provided that this clause shall not apply to any sum of money received.......
(iv) brother or sister of either of the parents of the individual......"
Hence receiving Gift from Uncle is not taxable.
but it doesnt say about receving gift from SON OF BROTHER... so receiving gift from NEPHEW would not be tax-free.
Section talks about receving and not giving... so defining vice-versa would be difficult.