Ummm...genetics don't determine metabolic rates in the manner you describe. If metabolism worked like height, then things like, you know, FOOD wouldn't cause cascading chemical reactions to regulate hormones, which in turn control things like proton leakage across mitochondrial membranes. Nor would exercise have any effect on your TDEE. Also, writing "they [genetics] don't prevent you from burning calories" immediate after stating "Genetics determine metabolic rates" is a full-on contradiction. By your logic, genetics are the sole determining factor in metabolic rate, a metabolic rate which is immutable like height, so of course it prevents you from burning calories. SMFH. Not that intelligent.