- Leah and Erin Sullivan, 4, are like 'two sides of the same coin' according to mum
- They do everything the exact opposite - from parting their hair to holding pens
- Mother Zoe, 42, said the pair are completely opposite in personalities too
- It is known as 'mirror image twins' and affects up to a quarter of identical twins Four-year-old 'mirror image' twins do everything from parting their hair to holding a pen in precisely opposite ways.
Leah and Erin Sullivan, from Inverness, Scotland, are like 'two sides of the same coin' according to their mother Zoe, 42.
While Leah parts her hair on the left, Erin parts hers on the right and both favour opposite hands for throwing or writing.
The pair even sleep in exactly the same position, but on different sides.
They are 'mirror-image twins' - a little-known phenomenon that means otherwise identical siblings are asymmetrical in their looks and how they move or interactThe phenomenon is believed to affect up to a quarter of identical twins, and Zoe found out her twins were affected last year.
Stay-at-home mother Zoe said: 'If their hair has been up, it's really hard to tell them apart!
'Leah's hair grew faster, but it wasn't until they were both about two and a half that their fringes started to grow out and I realised it parted on different sides!
'It didn't matter what you did, like trying to part it in the middle or on the other side, and really it's the only way you can tell them apart!
'That is when we realised they were mirror twins. Erin we think could be left-handed but Leah is definitely right-handed.
'After I noticed it I did look it up on the internet, it can be really extreme!'
She said Leah usually stands on the left in photos, with Erin on the right, and they walk with opposite dominant feet.
And when they face each other it looks exactly like they are looking in the mirror.
Their nursery also uses their unique hairstyles to tell the difference, but there could yet be more symmetries that reveal themselves as the girls grow older.
Zoe added: 'They are totally different in personality. Almost like different sides of the same coin.
'Every bit of personality Leah has, Erin doesn't, and vice versa.