Britney Spears' uncle isn't shocked by his niece's recent personal troubles - because she has reportedly been drinking and experimenting with drugs since her early teens. William Spears - the brother of the pop star's dad Jamie - claims the singer started drinking at the tender age of 13, and began smoking marijuana when she was just 14. But the substance use got worse as she rose to superstardom, according to her uncle, and he even partook in one of her alleged drug binges. He tells British newspaper The Sun: "I know she did cocaine on her 18th birthday - I was there. We were at a party in an apartment and I spotted her doing a line just before I did one. We smoked pot together too... "She has tried just about everything - cocaine, crystal meth, ecstasy..." And the 49-year-old welder fears Britney could be heading for an early grave like her grandmother Emma Jean, who committed suicide aged 31, if she doesn't seek professional help soon. He adds, "I'm not just a family friend or someone who claims to know them. I was there every day, working with them. I have seen all the terrible things happen... "Britney is in an unstable state of mind now and there is nothing anyone can do about it. She is not listening to anybody... "If people think she has reached the bottom, they are very wrong. Suicide is the bottom line for Britney."