Audit of books of accounts prepared by Relative

Only if its a company there is more serious issue to think about. since its not a corporate if the auditors  independence is not  affected. he can certify the financials.

No he cannot. He if does so, he would be guilty of professional misconduct under the Chartered Accountants Act. There is a specific provision in the second schedule of the above Act prohibiting a CA from expressing his opinion on the financial statements of an enterprise in which he or any of his relatives is interested.