Divine marriage is a feature of some religions that allows and encourages characters to marry close relatives 
.
Initially, two religions feature divine marriage: Zoroastrianism 
and Messalianism 
(a heresy of Nestorian Christianity). It is also available as a 
doctrine choice when reforming a Pagan religion.
Benefits of divine marriage
At the moment of a divine marriage, the ruler gains Piety: 50 for Counts, 100 for Dukes, 200 for Kings and 300 for Emperors. A similar amount of either Prestige or Gold is earned.
Some permanent opinion modifiers apply:
| Opinion modifier | Source | Source religion | Target | Value |
|---|---|---|---|---|
| Divine Marriage | Vassal | (divine marriage religion) | Liege | +5 |
| Divine Marriage | Vassal priest | (divine marriage religion) | Liege | +15 |
| Profane Marriage | Vassal | (NOT divine marriage religion) | Liege | -10 |
Strategies
Positive genetic traits
If using Ruler Designer, consider giving your starting ruler the positive genetic traits 
or 
, 
and 
. This does not reduce the risk of 
, but does improve the pool of potential spouses for your heir.
Mitigating the risk of inbreeding
Zoroastrians who choose to partake in divine marriages are at high risk of inbreeding. The risk of your dynasty dying out due to bad congenital traits (characters being inapt to rule, having fewer children and dying younger) is quite serious after a few generations. To prevent this you may:
- Prefer half-siblings (0.25) to full siblings (0.5) or offspring (0.5)
- Take concubines to produce heirs with more genetic diversity
- Marry dynasty members past child-bearing age
- Land dynasty members frequently to increase the pool of characters you can marry in the long term (unlanded characters are limited on number of children)
- Skip inept heirs, e.g. using feudal elective succession