To clarify - I've likely tamed a 3-4 dozen sets of boars to breed at my numerous bases resulting in many hundreds of offspring. The mating pair characteristics and offspring results are very familiar to me. Breeding has nothing to do with my issue.
What I believe happened two times at different locations was that a 1-star boar became a no-star boar during the taming (not breeding) process. Plus boars are not subject to the taming 'despawn' effect of night spawned wolfs to the best of my knowledge.

The 1st time it happened the untamed 1-star boar went into the pen with another untamed but no-star boar, I threw in the taming food, hung around the location doing base-stuff and went to start the breeding process when I got the notification that they were tamed. But the pen just held two no-star boars. These are earth walled pens and clipping weirdness doesn't apply. The first time it happened I thought I had brain farted and, like a politician, "disremembered" the star status'.

The 2nd time it started out the same with a wild 1-star & no-star plus enough taming food to tame both and start the breeding process. I missed the tamed notification but heard the piggy being born and went to see if it came out as a 1-star. Both boars and the piggy were no-stars. This was straightforward transmuting magic unless my brain farting is a chronic condition (DON'T contact my wife to verify this ).

From a game bug viewpoint I can see something getting mixed up when the "wild" boar gets changed into a "tamed" boar. It's not a very big deal but after +3600 game days on my one and only world and taming/breeding enough boars to supply the real world with bacon for a couple of centuries I was curious if anyone else had observed this seemingly rare phenomenon.

Originally posted by knighttemplar1960:

According to the wiki the game gives a 50/50 chance of the offspring having the same star level as either parent. I haven't done any experimenting with disparate star level livestock to confirm or deny that as yet.

Now I'm interested to see what happens when you breed a 2 star with a no star.

This is true only if the parents aren't the same lvl. If you breed a 2 star with another 2 star there is a 100% chance of getting another 2 star.

Originally posted by Isaac_Clark:

Originally posted by knighttemplar1960:

According to the wiki the game gives a 50/50 chance of the offspring having the same star level as either parent. I haven't done any experimenting with disparate star level livestock to confirm or deny that as yet.

Now I'm interested to see what happens when you breed a 2 star with a no star.

This is true only if the parents aren't the same lvl. If you breed a 2 star with another 2 star there is a 100% chance of getting another 2 star.

Both statements are true, but the first one could be worded a bit better. The offspring have a 50% chance of being the star level of the first parent, and 50% chance of being the star level of the second parent. If they are both 2 star, then there is a 100% chance of the offspring being 2 star. If the parents are different star levels, then it will be one of the two star levels with equal probability.

Now that others have mentioned it, 2 star boars can give birth to no-star boars if bred with a no-star. When I introduced 2 2 star boars into my singular of boar, once I had 4 or 5 2 star I wiped out all the no star boar I had. The next day I had 2 no star boar in my small singular of boar, so obviously the 2 star boar had given birth to no star boars.

According to the wiki the game gives a 50/50 chance of the offspring having the same star level as either parent. I haven't done any experimenting with disparate star level livestock to confirm or deny that as yet.

Now I'm interested to see what happens when you breed a 2 star with a no star.

Originally posted by knighttemplar1960:

According to the wiki the game gives a 50/50 chance of the offspring having the same star level as either parent. I haven't done any experimenting with disparate star level livestock to confirm or deny that as yet.

Now I'm interested to see what happens when you breed a 2 star with a no star.

You get either a 2* or a 0*.

I haven't conducted any detailed studies, but the 50% probability for each seems reasonable from my experience.

Awhile back the game was dropping boar meat & medium leather for deer I was hunting. It only happened when I did not loot the deer corpse right away. If I turned my characters field of view away from the deer I had killed, especially if I was a good distance away, the game would reward me with boar meat & leather after killing deer.

Generally the norm when breeding boar is a boar will produce offspring the same level as itself, even if it was bred to a lower level boar. The key to taming is to try and maintain close proximity and visual contact (in such a way as they cannot see you), while one is crouched and unarmed, especially when the game transitions to a new day. I have had creatures I was taming despawn while only being a few feet away from them, by turning away and losing them from my field of view, during the moment when a new day begins.

I found your post a little confusing insomuch that it read in such a way that it sounded like you were breeding boars while taming them? They cannot breed unless the taming process is complete in both animals, so if they had bred an offspring and you went back to find one of the breeding pair had transmuted to a no-star, then that occurred after the taming process.

Yeah, The Great Clip Escape. That's why all my animal pens have terrain walls now.
I guess it's still possible I'm losing my mind (or maybe just a bit more than has already been 'lost')

I haven't seen that happen but I have seen tame boars clip through the geometry and get out of my enclosure. Found a tame 2 star wandering around about 1,000 tiles away from the enclosure.