Marinus studied Biology at Leiden University and specializes in Molecular Biology, Cell Biology, and Animal Physiology. He received his PhD also at Leiden University on a Thesis about the expression of 2 receptor genes in Squamous Carcinomas - a specific type of skin carcer. He works at WUR since 1989. He has specialized in the biological understanding of (new) phenotypes. Specifically, he worked on the development of muscle tissue in relation to training and over training of horses, and meat and meat quality in pigs; reproduction problems in dairy cattle; and the relations between food and health of humans and animals.