How old is my child?

You are correct, or course.

If you need a compromise to keep the family peace: It's (regional?) German tradition to have an additional taller "Lebenskerze" or "Lebenslicht" ("candle of life") in addition to the smaller candles for the number of my birthday. It can be just a taller candle in a set like this, or one with numbers on the side decreasing down that you light every year until the child's 18th birthday. Those are usually gifted by birth or the first birthday.

I have no idea if it's a thing outside of Germany, but hey, you are a multicultural family, and it might appease the in-laws.

/r/AskEurope Thread