YOU SAID:

I am undoubtedly of lesser brain capacity

INTO JAPANESE

私は疑う余地なく脳の能力が低い

BACK INTO ENGLISH

I have no doubt my brain ability is low

INTO JAPANESE

脳力が低いのは間違いない

BACK INTO ENGLISH

There is no doubt that brain power is low

INTO JAPANESE

脳力が低いことは間違いありません

BACK INTO ENGLISH

There is no doubt that brain power is low