According to IMDb and Wikipedia Harpo was born in 1888. But Harpo, in his book "Harpo Speaks" said he was born in 1893. Can someone clarify?

Harpo was born in 1888. He was 75, almost 76 at his death.

The book must have made a misprint. Harpo was the second brother born. Chico in 1887, Harpo in 1888, Groucho in 1890, Gummo in 1892 and Zeppo in 1901. If he was born in 1893 he would be younger that Gummo and have been the fourth brother born, which he was not.