All the women at the baby group I went to looked down their noses at me because I had dreadlocks and was a bit hippie and they were 10 years older than me and much more 'with it'.
Within a couple of months of having 1st baby, I cut off all my dreads and started dressing 'sensibly'.
I was wrong about those mums - 8 years down the line, I count those mums as some of my best friends... we have attended each others weddings and been on holiday together, laughed, cried, drunk a LOT of wine and shared life. Our kids barely know each other but we are a strong, supportive bunch of friends, who are friends foremost and mothers second.
We now laugh at what we all thought of each other those first few sleepless, anxiety-ridden weeks we were getting to know one another at the baby group. I grew into myself as a Mum, gained confidence to be myself and not worry about what other people thought about me (re-dreaded my hair as soon as it was long enough again!)
Give the group and the girl who made that comment a chance - I know I've probably said much stupider things than that in my life. You might be pleasantly surprised.