Thanks for your query.
Please mention the semen analysis
report in detail.
Sometimes, men with abnormal semen analysis do have a genetic or chromosomal aberration.
Also, being cousins increases the risk of congenital anomalies in the offspring.
Have a karyotype
done for both of you, and ideally, the products of the miscarriage
also should have been karyotyped.
Kindly consult a genetic counsellor before planning a pregnancy
All the best.