What is the science behind the ectomorph, mesomorph and endomorph

Different body types (somatotypes) (A) Ectomorph, (B) mesomorph

Ectomorph Body Type: Diet and Workouts for Weight Gain - V Shred

What if an ectomorph and an endomorph have an offspring? Will they be a mesomorph? - Quora

Somatotypes Explained: What's an Ectomorph, Endomorph, and

Train For Your Body Type: Endomorph, Mesomorph And Ectomorph

Are the terms 'ectomorph', 'mesomorph' and 'endomorph' accepted and used by the scientific community? - Quora

Are endomorph, ectomorph, and mesomorph real and backed by sound science? - Quora

Are endomorph, ectomorph, and mesomorph real and backed by sound science? - Quora

Are body types like Mesomorph, Ectomorph, and Endomorph real, and how true or relevant are they when it comes to losing more than 50 lbs? - Quora