Let me explain what I mean by "genetic small LDL." I think it helps to illustrate with two common examples.
Ollie is 50 years old, 5 ft 10 inches tall, and weighs 253 lbs. BMI = 36.4 (obese). Starting lipoproteins (NMR) LDL particle number 2310 nmol/L Small LDL: 1893 nmol/L (1893/2310 = 81.9% of total, a severe small LDL pattern)
Stan is 50 years old, also, 5 ft 10 inches tall, and weighs 148 lbs. BMI = 21.3. Starting lipoproteins LDL particle number 1424 nmol/L Small LDL 1288 nmol/L (1288/1424 = 90.4% of total, also severe)
Both Ollie and Stan go on the New Track Your Plaque diet and eliminate wheat, cornstarch, and sugars, while increasing oils, meats and fish, unlimited raw nuts, and vegetables. They add fish oil and vitamin D and achieve perfect levels of both. Six months later, Ollie has lost 55 lbs, Stan has lost 4 lbs. A second round of lipoproteins Ollie LDL particle number 1810 nmol/L Small LDL: 193 nmol/L (193/1810 = 10.6% of total)
Stan LDL particle number 1113 nmol/L Small LDL 729 nmool/L (729/1113 = 65.4% of total)
Ollie has reduced, nearly eliminated, small LDL through elimination of wheat, cornstarch, and sugars, along with weight loss, fish oil, and vitamin D.
Stan, beginning at a much more favorable weight, reduced both total and small LDL with the same efforts, but retains a substantial proportion (65.4%) of small LDL.
Stan's pattern is what I call "genetic small LDL." Of course, this is a presumptive designation, since we've not identified the specific gene(s) that allow this (e.g., gene for variants of cholesteryl ester transfer protein, hepatic lipase, lipoprotein lipase, and others). But it is such a sharp distinction that I am convinced that people like Stan have this persistent pattern as a genetically-determined trait.