After I presented the problem of the birthdates of Ada May Gibson and her brother Arnold Gibson, Cindy Henry posted a comment that helps to clear up the issue. According to Ada May’s Baptismal Record, Ada May was born on 04 Aug 1859 in Canada, and according to Arnold’s Death Certificate, Arnold was born on 17 Aug 1859 in Vermont. Something is wrong here.
I found Arnold and Hattie Gibson in the 1910 and 1920 Vermont census on Ancestry.com. His age of 48/58 respectively provides an estimated birthdate of 1862.
I, myself, found Ada May in the 1861 Census of Canada East (Québec). She is enumerated on line 10:
The Gibson Households in the 1861 Census of Canada East (Québec)
SOURCE: Clark Gibson and John Gibson Households, 1861 Canada East Census (Québec), Parish of St. Georges de Clarenceville, Missisquoi County, page 253, lines 5-10 and 24-30. National Archives of Canada Film C-1297 Nominal. Microfilm FHL US/CAN Census Area 517397, Family History Library [FHL], Salt Lake City, Utah.
Click on the link for a PDF copy of the Gibson Households in the 1861 Census of Canada East (Québec). The census record shows:
Clark Gibson is enumerated with his wife and family on lines 5-10 of page 253 in the census of the Parish of St. Georges de Clarenceville, Missisquoi County, Canada East
Clark is a 37-year old blacksmith born in Lower Canada
Clark’s wife is Maryette Gibson, 27 years old, born in the U.S.A.
Clark’s children are Willard, 9 years old, born in the U.S.A.; Hannah, 7 years old, born in Lower Canada; Emily, 5 years old, born in the U.S.A.; and Addia [Ada May], 2 years old, born in Lower Canada
John Gibson [Clark's father] is enumerated with his wife and family on lines 24-30 of the same page in the same census as Clark
John is a 60-year-old farmer born in the U.S.A.
John’s wife is Sarah Gibson, 47 years old, born in the U.S.A.
John’s children are James, a 31-year-old laborer born in Lower Canada; William, a 24-year-old laborer born in Lower Canada; Martha, a 27-year-old spinster born in Lower Canada; Sarah, a 19-year-old spinster born in Lower Canada; and George, 12 years old, born in Lower Canada
Clark and his family are all listed as having no religion; John and his family are listed as being Wesleyan Methodists
This record shows that Ada May was 2 years old in 1861, so she was born in about 1859. This estimate agrees with the date on her Baptismal Record.
The census records that Cindy found indicate that Arnold was born in about 1862. Arnold does not appear in the 1861 census with the rest of the family, so it is likely that 1862 is a better estimate of his birth year than the 1859 date shown on his Death Certificate.
An examination of other census records between the 1861 Canadian Census and the 1910 US Census may help confirm these assumptions.
Since Clark Gibson’s family is listed as having no religious affiliation, it would be unlikely that his children would be baptized as infants. This may explain why Ada May was baptized at age 22 and why I haven’t been able to find Baptismal Records for any of Clark’s other children.