PSauce: Regal Family Tree

Hey everypony!
PSauce, Adam here.
It's been a while, hasn't it. But for Celestia and Luna, it seems as only a couple minutes. They've been around for so long, having to know almost everypony in their realm. Keeping records on every little detail.
Knowing so many ponies, it seems a little unheard of that they wouldn't have been married, if not only once. Why weren't they? Were they married in secret?
Was there a possibility of children? Could either of the royal sisters have had a child? It seems as though this would most likely be the case, as there have been rumors of a possibility of another alicorn; Princess Skyla: New toy,Fan Made
This is, obviously thanks to the color scheme, going to be the daughter of Princess Cadance and Shining Armor. However, Cadance, according to the comics, was adopted, and was once just a pegasus. This means that Celestia could technically turn any pony she wanted into an alicorn. Thanks, M.A. Larson. But, there is still room on the show for a possibility of something else. All that is stated is that in the show she is Celestia's niece.
However, she's only about 27-30 years old, and therefore Shining Armor is as well. Since both of them seem to be around this height, we can agree they were born around the same time.
But here's the catch, Blueblood has an almost identical stature, yet a bit beefy in the chest. So, we can agree that they are the same height/age. If this is so, then we can agree that Blueblood, Cadance, and Shining Armor are all the same height.
Now, Faust explained that Blueblood is "far removed," and that Celestia and Luna have no parents to outrank them nor any siblings. And, since Luna was on the moon during this time, this question still remains: How are all of them related in the first place?
I've come up with a few suitable solutions, but almost all of them are backed up by no evidence.

My theories on whom the parents are:

1) Obviously, I believe there is somepony we don't know about. There has to be another alicorn Princess out there. It could be Chrysalis for all I care. All I want is answers(only watch the first twenty seconds).

2) Luna had them over 1000 years ago, and they are immortal. What else is there?

My theories on how the rest of the bloodline is set up.

1) I think that Blueblood/Shining Aromor and Cadance are nonidentical twins and the rest of my theories tie into this. Same age, same stature, and they both have that kind of presence about them that you know crap is about to go down. Personalities don't matter, but what the heck do I know about genetics.

2) Shining Armor and Blueblood may be different, but let's face it. They were probably switched at birth. This explains why Shining Armor gets along so well with Cadance, because they were actually born from the same mother, they just don't know it so they think it's fine to marry. Again, apart from being a stallion, they are very similar, even personality wise. And even though their coats aren't exactly similar, neither is Twilight's to SA's. Speaking of Twilight's family, maybe Celestia knew about the Princess thing all along and purposely switched the children according to her plans.

3) Blueblood was Celestia's son, but she didn't want anypony to know due to the press and media and formality and all that junk. Therefore, nephew is just a cover up. Cadence I am happy as accepting her being adopted, but then don't turn her into an alicorn. Also, apparently Luna and Celestia were born alicorns, so why isn't anypony else?

Those were fun to think about, but here is the most legitimate answer I can come up with, supported and all.

I believe that Celestia takes in children through that school program and refers to them afterwards as nieces and nephews to anypony whom doesn't know as compensation for her loneliness. Or at least, she used to.
I believe that Cadance and Blueblood are connected somehow, and this is it. They probably brawled it out, trying to beat each other out for next heir to throne. Then she took in Sunset Shimmer, whom turned evil, and Celestia just tries to forget about her as a lost child, an experiment gone wrong. Then she took in Twilight. Since Twilight got Luna back, Celestia had no more of a reason to keep the program going, and is the reason Twilight was the last one to come through it. Unless another pony is announced as going through the program later in the season, this is the most logical answer I can come up with.

Well, that's all I can say on that matter. If you have other ideas, put them in the comments below. If a story is inspired by this, please put a link to this in the description somewhere.
And this is all because of reading A Night On Deck at 3 AM...
~Boost was here