Owned his first club as a two year old, when he would play with a little putter, but really started playing at the age of six.
His parents ran a golf club restaurant at Burge Overbach in Cologne.
A five-time European Tour winner, his biggest victory came in China at the 2014 BMW Masters, which propelled him to a career-high seventh place finish in the Race to Dubai.
Also has a World Cup win on his CV after partnering fellow German Bernhard Langer to glory in Barbados in 2006.
Returned to the Challenge Tour in 2021 after losing European Tour playing rights. Captured the hearts of the golfing world as he played 13 tournaments in a row before triumphing at the Le Vaudreuil Golf Challenge.
His victory in France earned him the final spot at The 149th Open at Royal St George's the following week, where he quickly became a fan favourite. Siem carded a three under par 67 on his 41st birthday to sit T9 after the first round. He remained inside the top ten after the third round before eventually finishing in a share of 15th.
Finished 15th on the 2021 Road to Mallorca Rankings to earn a return to the DP World Tour the following year.
Made his 500th DP World Tour appearance at the 2023 Singapore Classic and two weeks later returned to the winner's circle as he triumphed at the Hero Indian Open, more than eight years after his last win in China.