In Illinois, it is generally illegal for first cousins to marry, but there are two specific exceptions:
Both parties are 50 years of age or older, or
Either party is certified as permanently and irreversibly sterile by a licensed physician.
This means that first cousins under 50 who are not sterile cannot legally marry in Illinois. The law applies regardless of the gender of the individuals involved. The restriction is rooted in longstanding cultural taboos and outdated scientific beliefs about genetics, though recent research suggests the risks of birth defects from cousin marriages are lower than previously thought.
Second cousins and more distant relatives are not subject to these restrictions and may marry without limitation in Illinois.
Table
| Relationship | Legal to Marry in Illinois? | Exceptions |
|---|---|---|
| First Cousins | No | Yes, if both ≥50 or sterile |
| Second Cousins | Yes | None |
Key Points
- First cousin marriage is only allowed if both are at least 50, or one is sterile.
- No such restrictions exist for second cousins or more distant relatives.
- The law applies equally to same-sex and opposite-sex couples.
So, unless one of the legal exceptions applies, marrying your first cousin is illegal in Illinois
Sources
[1] https://www.ilga.gov/legislation/ilcs/documents/075000050K212.htm
[2] https://www.illinoistimes.com/news-opinion/why-cant-cousins-marry-15982640
[3] https://www.yahoo.com/news/legal-marry-first-cousin-second-161614122.html
[4] https://www.yeklaw.com/blog/2024/july/immigration-and-marriage-between-cousins/
[5] https://en.wikipedia.org/wiki/Cousin_marriage_law_in_the_United_States
