Hi my DD is 9 months old and still wont drink o...

Hi my DD is 9 months old and still wont drink out of a straw. I was just wondering at what age your child/ren started to drink out of a straw and did they just do it on their own or did you somehow teach them? I have started giving her smaller teats on her bottles as she has been on big teats from the day she was born so i thought the smaller teat would encourage sucking on a smaller area.... If anyone else has any ideas i would love to know... She does have a cup with a straw but she loves chewing on the straw instead of sucking it lol...