Is open about having ADHD, explaining, "When you have ADHD, you overthink." If he has structure, it keeps him from overthinking. Feels at ease on the golf course and says of managing his ADHD, "I understand me as a person now. I've got a lot of things in place if I feel a certain way or things are getting too overstimulated for my brain. I feel much better that I understand myself, and I think it's played a massive part in my career and my success."

First visit to a driving range was around the time he was five years old with his father, Angelo, who was testing out a set of clubs he was gifted for his 40th birthday. Angelo recalls, "My wife, Marie, bought me some cheap clubs... she said I needed to relax and take up a sport. I went to the driving range at Pease Pottage and took Marco along with me. He just picked it up ad drove it straight down the fairway!"

Following the driving range visit, Angelo eventually set Marco up with lessons at Mannings Heath Golf Club. Marco went on to represent the club in local matches, and made headlines in 2008 when, at only 10 years old, he won a match for the club's team in the Sunday Mail Classic Cup.

Was a talented soccer player in his youth, earning invitations for "trials" with Southampton and Reading. He played for Chesworth Rovers in Horsham, England, and reportedly scored 75 goals in a single season. Penge recalled, "For a while, I wasn't sure whether I wanted to be a footballer or a golfer, but golf won through in the end."

Wife, Sophie, won the 2016 Ladies' British Open Amateur Stroke Play Championship (operated by The R&A from 1969 through its final playing in 2017) and helped England win the 2017 European Ladies' Team Championship. Sophie also represented Great Britain and Ireland at the 2018 Curtis Cup. Sophie announced her retirement from professional golf in 2022.

Marco and Sophie won the 2016 Sunningdale Foursomes, an open foursomes tournament contested at Sunningdale Golf Club -- which is known for hosting multiple Senior Open Championships, Women's Open Championships, and the 1987 Walker Cup.

Represented England at the 2016 European Amateur Team Championship, as well as three European Boys' Team Championships (2013, 2014, 2015).

Won the 2015 Scottish Amateur Stroke Play Championship. Colin Montgomerie (1985) and Tommy Fleetwood (2009) are notable past champions of the event.

Won the McGregor Trophy (also known as the English Boys Under 16 Open Amateur Stroke Play Championship) in 2013. Justin Rose (1995) is a notable past champion of the event.

Competed in the "Boys 9" division of the 2007 U.S. Kids Golf World Championship in Pinehurst, North Carolina, finishing T24. Sahith Theegala finished fourth in the same division that year.