There's at least one genotype that can't handle high fat diets, hyper fat absorbers. A high fat diet for these people would promote obesity, diabetes, CVD, etc. And their blood work would get worse. For this genotype a low fat diet is advisable.

But for everyone else, it doesn't matter much. Healthy people meticulously regulate fat intake by various means. Low fat absorbers just poop most of the fat out. Really, for most people, (besides trans fats) it just doesn't matter much as long as you have a good balance of (mono)(un)saturated fats and get your essential omegas.

What most people could use more of is fiber and vegetables. Very solid way to lower trigs and cholesterol and it works regardless of genotype.