Out of curiosity, inspired by this thread I have looked at some trees with my 3x grt grandfather in them (the relative I'm currently working on). The first tree on the list has a lot of sources. However; my 3x grt grandfather was born in Ayrshire, Scotland in 1805, he married in Ayrshire in 1842, spent time in Edinburgh and INdia and died in Ayrshire in 1888. Now this tree has him with the same parents and wife but born in 1792 in Grafton Vermont, the 'proof' of this is the 1871 and 1881 census returns, both of which I have and state he was born c 1805 in Ayrshire, I also have his baptism, matriculation, employment records, death cert etc which all agree with year and/or place of birth as appropriate.
This tree then has him in New Hampshire, USA in 1810, 1820, in 1810 he was living in Ayrshire according to his school record (that's the year he started school), in 1820 he was at Edinburgh University, 1830 he was in India according to his service record (army surgeon).
In this tree he also apparently have a son in Vermont in 1816 (remember they have him in NEw Hampshire 1810 and 1820), he was 11! in 1816.
The tree then has him in Vermont in 1830 and 1840. They have attached the correct wife but not a marriage. They then have the correct births for 5 of his children between 1845 and 1861, correct death for his wife in Ayrshire Scotland but he dies a year later in Wisconsin, USA and is buried 3 days later in Ayr Ayrshire. Oh and his son John dies in 1895 in Iowa, he didn't he died in Calcutta in 1902, I have multiple documents, obituaries and biographies to confirm this.