What's the best way to tackle a relative who has an opinion on everything related to the way I bring up my children?

There is always someone who does this!!!! I know it is irritating, frustrating etc etc but have an open ear. Ignore stuff that contradicts and you already know is the best practice. But if it contradicts and you do not know about it, it might be worthwhile to do some googling. Best way it to hear out else you will end up discussing even more and frustrated even further :)