Genetic factors are affecting his illness.

He is proud of the achievements of his ancestors.

I often eat alone.

I am enjoying eating alone.

He lives alone in the mountains.

He escaped from the hustle and bustle of the city and chose a life of living alone.

This is an isolated case, different from other cases.

He likes to take a walk in the park at dusk.

This disease is caused by the gene.

I am very interested in genetics.