It’s normal, particularly for people who have had babies and particularly those, like your parents and in-laws, who are close, to assume that they are experts on babies.
It’s true that they do have experience and they probably also have some knowledge that you, as a new mum, can use. However, it’s important to remember that this is your child, and that you are the one who has the final say about just about everything to do with raising him or her.
Once you’ve acknowledged your responsibility, and your instinctive ability, as your child’s mother to know and do what’s best for him or her, it’s a lot easier to see that interference as advice. Use what you want to from it and discard what you don’t, but don’t let it get to you. You may even find that you start to enjoy talking about all things baby related with every friend, relative and colleague.
Just remember that as long as you are happy with your babies health, development and happiness, and as long as his or her needs for love, sustenance and security are being met, it doesn’t matter if a friend or relative says that you’ll spoil your child by picking them up, or if they give you ludicrous home remedies to common problems. You can simply choose to ignore it, and follow your instincts.