Dennis's mother had consumed a substantial amount of alcohol during her pregnancy; dennis's intelligence is below normal, his growth is slowed, and his facial features are slightly deformed. ellis's mother had also consumed a small amount of alcohol, and ellis shows some, but not all, of the problems dennis displays. dennis suffers from ; ellis suffers from

Dennis suffers from fetal alcohol syndrome.

Ellis suffers from fetal alcohol effects. Fetal alcohol syndrome is termed as a severe form of a condition. People who have fetal alcohol syndrome may have problem with their vision hearing, memory, attention span, and abilities to learn and communicate.
Fetal alcohol syndrome can be caused when a pregnant woman drinks alcohol, it passes across the placenta to the fetus. Now that the body of developing fetus does not process alcohol the same as an adult.
 The alcohol becomes more concentrated in the fetus and prevents enough oxygen and nutrition from getting to the fetus vital organs.

They must use the scientific method