If it is the literal pasting of the data that you are having issues with, this is most likely caused by some type of software interference.
If it is the display of the information that is the issue (not displaying as a table), then this is due to the markup used on WikiTree. WikiTree uses what we call wiki-markup (or wikitext) which is a specialized syntax used to format a page, where items like tabular indenting have no affect on display. For this reason, we uses special symbols and text to format pages, such as:
{| border="1"
! Name
! Age
|-
| Bob the Builder
| 19
|}
which creates:
Name |
Age |
Bob the Builder |
19 |
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If you let us know which one you are having issues with, we can try and help further.