What is a double first cousin?

Exploring the Complexities of Double First Cousinships

If you’ve ever been curious about genealogy and family relationships, you may have heard of double first cousins. But what exactly is a double first cousin? This blog post will explain the details behind this complex family relationship and why it’s important to understand its nuances.

Double first cousins are two people who share both sets of grandparents in common. It’s important to note that double first cousins are not just cousins one degree higher than regular first cousins—they’re a totally different kind of familial relationship altogether. To understand why, let’s look at an example.

Let’s say Person A has two siblings, Person B and Person C, and all three siblings have two children each. In this case, the children would be considered double first cousins—they share both sets of grandparents (Person A’s parents). However, if Person B and Person C were only half-siblings, their children wouldn’t be double first cousins; they would simply be regular first cousins because they don’t share all four grandparents in common.

Double first cousin relationships can become even more complex when other relatives are added into the mix. For instance, if one set of grandparents had more than two children (e.g., four or five), then those additional relatives could potentially be related to each other as well—even though they’re not technically blood relatives! That’s why it’s so important to carefully examine your family tree before making any assumptions about your relationships with other members of your extended family.

Double first cousin relationships can also lead to some interesting genetic outcomes. Research has shown that the closer two individuals are related by blood (i.e., the closer their shared ancestor is), the greater the chance that they will share certain traits or diseases in common due to their shared genes. In fact, studies have suggested that double first cousin relationships are associated with a higher risk for certain birth defects than regular first cousin relationships—so it’s important to be aware of these potential risks before getting too close with someone who shares both sets of your grandparents in common!


Double first cousin relationships can get complicated quickly, but understanding them is key for anyone looking to explore their genealogy or better understand how genetics plays a role in disease risks within their families. By familiarizing yourself with what makes a double first cousin unique from regular cousinships, you’ll be able to make more informed decisions about how close you want to get with certain members of your extended family tree!


1. What is a double first cousin, and how does it differ from other types of cousins?

A double first cousin is two individuals who share both sets of grandparents in common. Compared to regular first cousins, which only share one set of grandparents, double first cousins have a closer genetic relationship that can potentially be associated with certain risks or other unique features.

2. How do double first cousins affect my family’s genetic makeup?

With two sets of shared grandparents, double first cousins may have a higher likelihood of sharing common genetic traits or diseases. This is particularly true if they are more closely related by blood and their shared ancestors are relatively recent. However, more research is needed to better understand these relationships and their implications for family health.

3. What are some strategies for managing double first cousin relationships?

There are a few different approaches that you can take when dealing with double first cousins or other more complex family relationships. You may want to examine your family tree carefully, talk to your relatives about their health and genetic history, or consult a genetic counselor for additional guidance. Ultimately, it’s up to you to decide how closely you want to be involved with these relationships and what best fits your individual needs and goals.