Why did the changelings all look similar?

[Ar-Pharazon]

Her character was just found

Spoiler: spoiler

floating face down in the lake.

That's not the great link?

 

[Lynx]

I just assumed that the second theory was right and they were mimicking Odo to make him feel like he'd really found his people. At first anyway. After that it became their default when dealing with people from the Alpha Quadrant because Odo had already established what they expected a Changeling to look like.

We at least know the hairstyle doesn't come naturally to them because Odo got that by mimicking his dad, Mora Pol.

I think that you are right in that assumption. When Odo showed up and they saw how he had adapted to look like the "solids", they did the same.

Or maybe they were mocking him and the Federation people by looking that way since they obviously could change their appearance to look exactly like a human, like Ambassador Krajensky in The Adversary, Admiral Leyton in the episode Paradise Lost and even another species like the Romulan Colonel Lovok in The Die Is The Cast.

As for Odo's hairstyle, I think that he was even more inspired by 20th century rock icon Jerry lee Lewis than Dr. Mora!