My kid's development has always been ahead of other kids of the same age group since infant, and somehow I feel other mummies in the chatgroup are jealous about it ? Does anyone feels the same way?

It is normal and nature for parents who think their kids are the best or vice versa. Personally, we encounter a few parents who comments loudly that their child dance or act the best in the whole class while other kids are just fooling around etc right in front of other parents or the children itself. To me, I don't care at all and do selective reading only. If they comment due to jealousy of my child, I will just adjust my feeling/emotion accordingly to explain to my child if she happens to hear that. Every child is different and has it own song of life. I prefer to let them blooming the way they are. Don't let other dictate how you should feel about your child and yourself. Childhood is very short, I rather spend all my times playing and building bonding with my children then caring about what other thinks.