When was Lowell Simpson Born?

My Grandpa Lowell passed away when I was only 11 years old. My only impressions of him came from a visit to us in Ottawa and a stay in one my my Uncle Wayne's hotels. To me, he was a warm man who could easily make me laugh.

However, my research has left me with a question? When was he actually born? I suspect it wasn't really when everyone thinks.

The records are consistent that his birthday was October 19. However, the year is harder to determine.

• The 1910 U.S. Census, taken April 15, 1910 claimed he was 5. The information on this census includes number of years married and number of children born and surviving  so it was probably provided by a parent. This would place the birth year at 1904.
• The 1921 Canadian Census stated he was 15, however the number is hard to read; it could be 16.  Censuses are almost always in the spring or summer so this would place it at 1905 or 1904. 
• He stated on a May 24, 1923 border crossing record that he was 18; placing birth year at 1904.
• He stated on an Aug 30, 1924 border crossing record that he was 18 (still!), placing birth year at 1905.
• He stated on an August 31, 1928 border crossing record that he was 26, placing birth year at 1901.
• His army discharge papers claim that on August 20, 1942 he was 34 years, 10 months, placing birth year at 1907.
• He stated on a January 9, 1947 border crossing record that he was born on October 19, 1907.
• His stated on a sworn statement, confirmed by his brother-in-law, Joseph Strachan, that he was born October 19, 1904.
• He stated on a January 9, 1948 border crossing record that he was born October 19, 1907.
• His obituary stated that he was born October 19, 1907.

So when was my grandfather born?