Thomas is guilty of the "sibling contrast effect", exaggerating the true magnitude of the differences between his children.
There are two unique sorts of contrast effects, which will be called sibling contrast effects and rater contrast effects. sibling contrast effects are the inverse of imitation. Sibling imitation is exactly what it sounds like-sibling mimic each other's conduct, expanding their comparability. Sibling contrast happens when one sibling does the polar opposite of the other, bringing about diminished kin comparability.