If you want to give your parents-in-law a birthday present, you can ask your wife first. She should know better than you. You can also see what gifts other relatives gave you. If you know the size of your parents' clothes, you can send clothes and shoes. If you like cooking, you can send out recipes or some seasonal fruits. Chatting with them more will help you understand their preferences. If it is better to have children, they will tease them. I usually have contact, and I want to close the distance before my birthday.