They're most likely related, distantly. I know it was never stated that Chiyo is directly related to Gaara, by she probably was. Their appearances are both similar to the 4th Kazekage. I assume Sasori might be Gaara's uncle, or 2nd cousin. Something alone this lines.
Don't get me wrong, it's clearly just a theory. It was never stated, it just holds up to reason. It may be something Kishi had in the back of his mind, but hasn't found a good place to explore it. He could be holding it back for a later story line, or something.
They're very similar. Both baby faced as young adults, similar hair styles that also look like the 4ths. Similar-ish hair color. I'm not saying they're identical, but the similarities are certainly there.
Their hair is kinda similar.. If u add no eyebrows, the "Love" sign on the forehead and the
Shukaku's Eye Marks they'll more related in appearance... IMO
They May be related, Because of the Hair, and According to the manga, everyone with Red hair is Uzumaki!
So in a sense, the Two of them Are probably from Uzumaki, being Distantly related