@waffels,
Most of us lie to smooth our way through life, for examp I once applied for a factory job after being unemployed for several years and when the interviwer asked me what on earth i'd been doing for all those years, I lied and told him "I was in a rock group trying to make the bigtime" and he seemed to swallow it and set me on. The truth was i'd been bumming around the country looking for hippy communes to join and have never touched a musical instrument in my life!
In your case, if they spot your scars at the medical i'd probably say something like- "I got them when I ran into a fence while out jogging".
Remember, the recruiter must have liked you and wanted you, so you'd be simply following his orders by fibbing..