How autistic relatives shape autism odds

People with an autistic relative stand an increased chance of having autism with or without intellectual disability (ID). The more closely related the autistic relative, the higher the odds; the strongest association is with autistic mothers.

Odds

ratio of autism with ID

Odds

ratio of autism without ID

Father

2.7

Mother

19.6

10.8

Brother

6.7

6.8

Sister

8.2

6.4

Half-brother

2.3

2.5

Half-sister

2.5

2.2

Uncle

2.2

1.9

Aunt

1.8

1.3

Half-uncle

1.7

2.4

Half-aunt

1.3

1.8

First cousin, male

1.8

1.5

First cousin, female

1.7

1.3

Half-cousin, male

1.4

Half-cousin, female

1.1

0.9