The Catholic Church did not allow marriage in certain circumstances called “impediments”. Examples of such impediments were if the one party had a living spouse or had committed homicide, one party was not Catholic and finally if bride and groom belonged to the same family.
The proximity of the relationship between people of the same family was measured by degrees of consanguinity, that are the number of steps needed to get from them to a common ancestor.
| Degree | Relationship |
| 1º degree: | Children and their parents |
| 2º degree: | Brothers and sisters, grandparents and granddaughter / grandson |
| 3rd degree: | Uncles and aunt with nephew and niece. Great-grandparents with great-grand-son / great-granddaughter |
| 4th degree: | First cousins, great-uncle and grandniece / great-aunt and grandnephew |
The consanguinity degree should not be confused with the relationship degree (used in civil records). See note below for details.
In addition we have the degrees of affinity on family relationships, where a person would marry a family member of his /her deceased husband or wife.
Finally, we find the degrees of spiritual relationships, when a godfather/godmother wanted to marry their godson / goddaughter, or when godson and godmother wanted to get married. These also required a dispensation.
Catholic Church did not allow marriages up to the 3rd degree and at the same time did not oppose to marriages higher than 5th degree. For couples belonging to the same family with a 4th degree of consanguinity it was possible to obtain a papal dispensation, allowing them to get married.
These dispensations are interesting for the genealogist because they explain exactly how the couple is related; giving their lineages back to the common ancestor. Sometimes they are very complete and include genealogical graphics and biographic information about the ancestors.
Dispensations are noted on the Church marriage records but they are not found at the parish level, but maintained at the diocesan level.
http://www.hispanicancestors.com
Note: Consanguinity degrees should not be confused with the relationship degrees. These are the details for the relationship degrees:
| 1º degree: Children and their parents. | Also applicable to brothers and sisters |
| 2º degree: first cousins | Groom and bride are grandson and granddaughter of the same ancestor |
| 3º degree: second cousins | Groom and bride are great-grandson and great-granddaughter of the same common ancestor. |
| 4º degree: third cousins | Groom and bride are great-great-grandson and great-great-granddaughter of the same common ancestor. |
| 5º degree: fourth cousins | Groom and bride are 4th grandson and 4th granddaughter of the same common ancestor. |
This is just the basic pattern and we find a lot more of complex relationships degrees mixing the different levels. I will give a few examples:
· 1º mixed with 2º degree (Son/daughter of a certain ancestor marries a granddaughter/grandson of that same ancestor),
· 1º mixed with 3º degree: marriage between great-uncle and grandniece / great-aunt and grandnephew (Son/daughter of a certain ancestor marries a great-grandson / great-granddaughter of that same ancestor).
· 1º mixed with 4º degree: marriage between great-uncle and daughter of his grandniece or grandnephew / great-aunt and son of her grandnephew or grandniece (Son/daughter of a certain ancestor marries a great- great-grandson of that same ancestor)
· etc.
