I was 16 when I had my first boyfriend and I kept it hidden from my parents though im not sure why. It was the summer after gcses and whenever I met him or went round his house I just said I was meeting my friend. I know they had suspisions, my dads receptionist saw me walking back from his which was quite far away and he asked where I was coming from. And they both though it was weird for me to be out with this friend all the time and she never came round here. They knew I was lying, but never said. I think they didnt want to embaress me. They also knew the guy, I used to work with him and he chatted to my mum quite regulary.
Its very devious though, and dangerous. But it does make it kind of exciting!
When I met my current boyfriend 2 years ago at 17 I told my family about him straight away, I decided no more lies.
I think people should only lie to their parents about seeing someone if their family is either strict or religious.