In 1888, Keller attended the Perkins School for the Blind. In 1894, Keller and Sullivan moved to New York City to attend the Wright-Humason School for the Deaf and Horace Mann School for the Deaf. In 1896, they returned to Massachusetts and Helen entered The Cambridge School for Young Ladies before gaining admittance, in 1900, to Radcliffe College, where Standard Oil magnate Henry Huttleton Rogers paid for her education. In 1904, at the age of 24, Keller graduated from Radcliffe magna *** laude, becoming the first deaf and blind person to graduate from a college.

I find it hard to believe a 19 month old child would be capable of such deception.

Also why would she continue to try to deceive the world for her entire life?

The story of Helen Keller is the story of a child who, at the age of 19 months, suddenly lost her hearing and vision, and who, against overwhelming odds and with a great deal of persistence, grew into a highly intelligent and sensitive woman who wrote, spoke, and laboured incessantly for the betterment of others.

She is/was not the only person who is/was deaf & blind. There are many other cases.

Here is a link to her story on Wiki – if you’re interested….