conceiving

Finding out dad isn't your biological father

Up to 3 per cent of people are the genetic offspring of someone other than the man they think, according to UNSW Professor Rob Brooks and Swinburne University of Technology Professor Michael Gilding, who have both studied misattributed paternity.

Possible scenarios include mum having multiple sexual partners at the time of the child's conception, undisclosed adoption, medical mistakes, the parents using a sperm donor to conceive or "dad" arriving on the scene when the child is too young to remember.

In some cases, dad may not even realise himself.