For a true "relationship" to exist, there must be an ancestor who is common to both individuals. If you examine the chart below, for example, the Common Ancestor is box 1 on the horizontal scale as well as box 1 on the vertical scale.
Let us suppose that you have a great grandson of that common ancestor, as seen in box 4 of the horizontal scale, and you want to know that great grandson's relationship to a great-great-great granddaughter, who may be seen in box 6 on the vertical scale.
If you follow box 4 down to where it meets line six, it tells you the relationship - they are second cousins twice removed!
|1||Common Ancestor||Son or Daughter||Grandson or Daughter||Great Grandson or Daughter||2nd Great Grandson or Daughter||3rd Great Grandson or Daughter||4th Great Grandson or Daughter||5th Great Grandson or Daughter|
|2||Son or Daughter||Siblings (Brother or Sister)||Nephew or Niece||Grand Nephew or Niece||Great Grand Nephew or Niece||2nd Great Grand Nephew or Niece||3rd Great Grand Nephew or Niece||4th Great Grand Nephew or Niece|
|3||Grandson or Daughter||Nephew or Niece||First Cousin||First Cousin Once Removed||First Cousin Twice Removed||First Cousin Three Times Removed||First Cousin Four Times Removed||First Cousin Five Times Removed|
|4||Great Grandson or Daughter||Grand Nephew or Niece||First Cousin Once Removed||Second Cousin||Second Cousin Once Removed||Second Cousin Twice Removed||Second Cousin Three Times Removed||Second Cousin Four Times Removed|
|5||2nd Great Grandson or Daughter||Great Grand Nephew or Niece||First Cousin Twice Removed||Second Cousin Once Removed||Third Cousin||Third Cousin Once Removed||Third Cousin Twice Removed||Third Cousin Three Times Removed|
|6||3rd Great Grandson or Daughter||2nd Great Grand Nephew or Niece||First Cousin Three Times Removed||Second Cousin Twice Removed||Third Cousin Once Removed||Fourth Cousin||Fourth Cousin Once Removed||Fourth Cousin Twice Removed|
|7||4th Great Grandson or Daughter||3rd Great Grand Nephew or Niece||First Cousin Four Times Removed||Second Cousin Three Times Removed||Third Cousin Twice Removed||Fourth Cousin Once Removed||Fifth Cousin||Fifth Cousin Once Removed|
|8||Fifth Great Grandson or Daughter||4th Great Grand Nephew or Niece||First Cousin Five Times Removed||Second Cousin Four Times Removed||Third Cousin Three Times Removed||Fourth Cousin Twice Removed||Fifth Cousin Once Removed||Sixth Cousin|