No, you don’t need to teach them to sleep alone. They are fine as they are!
The detailed answer:
This is one myth the “baby experts” love to throw about, the idea that you are doing your child a disservice if you don’t “teach” them to sleep. The fact of the matter is, you can no more teach a child to sleep than you can teach them to crawl or walk. Firstly, your baby slept pretty efficiently in the womb – they know how to sleep. Secondly, like crawling or walking, sleeping through is a developmental stage your child will reach when they are ready. No other species need to sleep train their young. Neither do we.
Read more here: