Influence of age gap and parents′ ethnicity on the sex of the first born child

The influence of parents' age gap and their ethnicity in the determination of the sex of the first born child is provided. A descriptive analysis was undertaken and χ2 test, association measures and logistic regression were applied to verify the relationship between variables. The chance that a male first child is born from a mother one to ten years older than the father is twice the chance of parents whose age gap ranges between 0 and 5 years, the father being the older. Further, the chance of a male first child born from an ethnically white male parent is approximately five times higher than that of an ethnically yellow one.