My elder sister looks exactly like me in that we are often mistaken.

[sania-baharat]

Are these two sentences correct?

My younger sister is very similar to me in that both of us are so optimistic that we tend to think positively towrads things happeng around us.

My elder sister looks exactly like me in that we are often mistaken.

 

[Raymott]

The first would be correct if the spelling was corrected.
The second is wrong. "In that" means "insofar as", "by virtue of the fact that". It is not the fact that you are often mistaken that makes you look exactly alike. The causation works the other way.

 

[sania-baharat]

It is not the fact that you are often mistaken that makes you look exactly alike.

I think I almost undertans what you mean. Does the following now make sense?

My elder sister looks exactly like me in that we both have got long black hair, small noses and square face shapes. In addition, my sister is the same weight and height as I am.

 

[GoesStation]

You probably mean you are often mistaken for one another. What you wrote means you are often wrong.

 

[Raymott]

I think I almost undertand what you mean. Does the following now make sense? [...]

Yes, it does.

 

[sania-baharat]

You probably mean you are often mistaken for one another. What you wrote means you are often wrong.

What is difference between "you are often mistaken for one another" and " you are often wrong"?

 

[sania-baharat]

Thanks Piscean. Such detailed explanation.
So, I meant:
My elder sister looks exactly like me in that we are often mistaken for one another.

 

[Rover_KE]

Say 'My elder sister looks exactly like me, so we are often mistaken for one another.