Contagion by Katherine MacLean.
From what I remember there were some astronauts that went to a planet
and everyone there looked very similar (if not the same)
She addressed a question to the tall colonist on outside sound. "What
should a person look like, Mr. Mead?" He indicated her with a smile.
"Like you." June stepped closer and stood looking up at him,
considering her own description. She was tall and tanned, like him;
had a few freckles, like him; and wavy red hair, like his. She ignored
the brightly humorous blue eyes. "In other words," she said, "everyone
on the planet looks like you and me?" Patrick Mead took another look
at their four faces and began to grin. "Like me, I guess. But I hadn't
thought of it before. I did not think that people could have different
colored hair or that noses could fit so many ways onto faces. I was
judging by my own appearance, but I suppose any fool can walk on his
hands and say the world is upside down!" He laughed and sobered. "But
then why wear spacesuits? The air is breathable."
The description of the faces seems very similar to yours ("Maybe they
all had red hair and similar skin tone but retained some different
But each face she looked at was the same. Watching them dissolve and regrow in the nutrient solution, she had only been able to guess at the horror of what was happening. Now she knew.
They were all the same lean-boned, blond-skinned face, with a pin-feather growth of reddish down on cheeks and scalp. All horribly—and handsomely—the same.
maybe it was if they removed their helmets they would start to change?
They were looking at Max. June stepped silently out of the tank room,
and then turned and went to the airlock. She opened the valves that
would let in Pat Mead's sister.