Gennaro started karting at the age of 5, and starting winning early in his career. In 1997 he won the Cadet Class Championship.
He then stopped for one year but on his return finished 4th in the WTP SA Championship. He then moved to the UK, where he raced Junior GP karts for 2 years.
Gennaro was the youngest driver to compete in the ROK World Karting Championships in 2006 and nearly won the 2007 SA Karting Championship, thwarted by a broken chain in the title showdown.
He moved to saloon car racing in 2007, competing in the super-competitive VW Polo Cup Championship, taking a pole and podium in his first season. In the same year, he competed in a round of the European Polo Cup, ending 9th (in a field of 32) on an unknown circuit in an unknown car. He was awarded Protea Colours in 2007.
The 2008 Polo Cup Championship took second place to his matric exams, ending 2nd in the title rankings, a feat he repeated in 2009. In 2010, he entered class T of the Production Car series, winning on debut and going on to finish 2nd in the championship.
2011 saw Gennaro again compete in class T, ending 3rd after updating to a Golf 6 mid-season 2012 was another strong season, before Audi gave him the opportunity to race his current car, the S4 quattro. In typical Highveld thundershower conditions, Gennaro claimed his first top-class scalp. In 2013, he claimed a win and three podiums.
After a spectacular debut under the Sasolracing banner in the opening round of the 2014 Bridgestone Production Car Championship, Gennaro leads the title chase after qualifying 2nd and racing to two second place results.