I've posted on other threads about this. My hair has always been baby fine and is thin as well, has been since my thirties. I've had tests for thyroid function and anaemia, but nothing's cropped up. My DGM and aunt had similar hair and my dad was practically bald by his mid-twenties, so I assume it's genetic. I've tried all sorts of pills and potions to little effect, had specialist extensions at a salon that offers treatment for people with alopecia and the like (they were excellent, but I had to trail down to London every 6 weeks for adjustments, which after a year or two got to be too much of a commitment and expense). I now just concentrate on trying to make it look better. Elvive Fibrology is effective to some extent, and I use Batiste Dry Shampoo to boost what I have - both are cheap and make some difference. The one thing that always annoys me is people saying you should just have a good hair cut at a top salon. If you have enough hair to be given a good hair cut, you haven't really got a problem! Best wishes (and I'll be watching the thread for any recommendations too).