When you check a sylestis lineage, it comes up with an inbred %. What does this mean?

It means that the same family member has appear more then once in it's lineage
For example, if you have a baby zolnixi with some inbreeding and you check it's lineage you might find that it's mother was bred with it's father and great grandfather, or the mother was bred with it's grandchild.

Oh, ok. Thanks! But, they can't really breed, right? They are to closely related? Aren't they?

Parent's can't breed with offspring, Nor can siblings breed with siblings.
Aunt's can breed with nephews, and Grandparents can breed with grandchildren, however.

You can't breed a pet:
- with its mother;
- with its father;
- with a brother / sister.

You can bred pets with grandparents, aunts, uncles, cousins, etc - that's what will give rise to an increase in inbred percentage.

As an example...

If you take four generated / tamed pets (A, B, C, D) and breed:
- A with B twice - producing AB1 and AB2; and
- C with D twice - producing CD1 and CD2.

You can then take AB1, AB2, CD1 and CD2 and breed:
- AB1 and CD1 twice - producing 2.1.1 and 2.1.2; and
- AB2 and CD2 twice - producing 2.2.1 and 2.2.2.

2.1.1, 2.1.2, 2.2.1 and 2.2.2 could be bred again with any of A, B, C or D (grandparents)
2.1.1 and 2.1.2 could be bred with AB2 or CD2 (aunts / uncles)
2.2.1 and 2.2.2 could be bred with AB1 or CD1 (aunts / uncles)
2.1.1 and 2.1.2 could be bred with 2.2.1 and 2.2.2 (and vice versa) (cousins? I'm getting myself a little confused)...
etc

At this stage, from what I can gather, inbreeding does not cause any ill-effects.

Thanks for explaining.

Can I just add a question to this?

At this point in time, does having a high inbreding number/percentage due anything negative to the pet? Like making them have lower base stats?

Nope, inbreeding does not do anything negative to the pet. We only have the inbreeding % there for information purposes.

The inbreeding does not affect the pet in any way. It's just to tell how many of the same parentage has been bred. Some users might not like a high inbred number. But other than that, the inbreeding does not affect the pets stats or anything.

Thank you both for answering!

I was worried higher numbers meant more issues (like in real life) and so I was trying to plan future projects around it but if it's a non-issue, I won't sweat it too much.