Gulenko said Dynamic types were more inclined to have moodiness. This is a true, but unsufficient observation that may lead to confusion.
Most inclined types :
As you can see, it's partly related to Sensing and Rationality. Keirsey wasn't really right on that point ("SJ = Melancholic"), but he wasn't that far of the truth.
- On the 2nd-4th variables groups (SP, SJ, NP and NJ), SJ is the most moody. Except that ESE's aren't really inclined to be moody.
- Gamma Quadra is the "moodiest".
- Negativists are more inclined to be moody.
- There seems to be a slight correlation between moodiness and Process.
- Introtims are more inclined to be moody. They have lower neurochemical activity. Moodiest Extrotim type is LSE.
- There doesn't seem to be any correlation between information elements and moodiness.
- Declarative types are slightly moodier.
- ST is slightly moodier.
- SEI-ESI quasi-identical pair is the moodiest.
- The least "moody" 1st-3rd variables group is EF.
Enneagram as somewhat a clear definition of moodiness. E4, E6, and E8 are moody. I put ESI on the top because it's the only socionic type which I don't have encountered with variants other than those. I only know ESI-6 and ESI-8 dudes/girls yet.