Wedding etiquette states you shouldn’t wear white on someone else’s big day.

But this mother-in-law doesn’t seem to have got the memo.

In a picture posted to a Wedding Shaming forum, Reddit users couldn’t tell which woman was the bride.

The groom’s mum is dressed in a floor-length lace frock – and she even has a veil-like shawl around her shoulders.

Meanwhile, the bride is wearing a plunging white gown with a large tulle skirt.

Redditors were fuming at how similar the pair look – with some branding the mother-in-law “tacky” because of her outfit choice.

People reckon the mother-in-law looks too much like the bride (left)

The post racked up 3,000 upvotes – and the vast majority of commenters blasted the mother-in-law.

One responder wrote: “Yikes, this is bad. It looks like there are two brides here.

“Lacy, full length AND embellished, talk about attention seeking. Did someone accidentally spill their red wine?”

Another said: “It took me a good 10 seconds to work out which one was the actual bride ( then I noticed the emoji expressions).”

And a third agreed: “This is beyond tacky, it’s so creepy. I will never understand mums like this.”

While many thought the mother-in-law was out of order, others couldn’t help but compliment her dress.

One Redditor admitted: “I actually LOVE the dress. But it’s totally inappropriate in that colour for a mother of the bride.”

A second said: “The elegance of the groom’s mother’s dress makes the bride look like she has on a prom dress in comparison to me. Poor girl.”

And another added: “The worst part is I think the mother’s dress is better.”

So what do you make of the outfit choice? Let us know in the comments section below.