I think it's worth asking. Having had more children younger doesn't increase your risk, but having had more sex partners does (and unfortunately, rightly or wrongly, I think health professionals assume that if you had kids younger that you started to have sex younger and with more people than someone else your age). The abnormal cell changes they are testing for are caused by the HPV virus, which is a sexually transmitted infection. Something most of us have been exposed to by the time we're 30, but not all strains cause cervical cancer, just the most high risk ones. So certainly, I think it's worth asking about if you want to have it done. It could be reassuring and it's not really a big deal to have done. It's unlikely that at your age that you would have anything come up because serious cervical cell changes can take as long as 10 years to develop from when you were first exposed (when you first became sexually active). That's why they don't offer them to 18 year olds, because most 18 year olds haven't been having sex long enough or at all for the test to show anything. But there have been a few high profile cases of young women dying of cervical cancer recently, so it's always possible. They might ask you some questions to assess how at risk you are for cervical cancer (things like smoking also increase your risk if you have HPV, along with family history) and then decide to offer it or delay it, but if you want, it's worth asking about.
