Lannanta - having taken a look out of curiosity I find that the quoted information appearing in Ancestry Trees is so stupid as to not warrant comment!
So - let's start with something that bears some resemblance to common sense.
From the Tapley-Soper transcript of Camborne Parish Registers produced by the Devon & Cornwall Record Society we have the following baptisms occurring at Camborne between the years 1665 and 1706:-
1st November 1685 - John son of John Glasson
of GwinnierApril 1691 - William son of John Glasant <====
17th January 1701 - Jane daughter of Charles Glasant
(There are several baptisms of children to a John Glasson up to 1661 and then an unnamed child baptised in 1664. This last does not appear in the BTs. This appears to be an earlier John Glasson.)
John Glasson was not married at Gwinear but obviously he was resident there at least for a time so I have searched the Gwinear Parish Register from 1664 to 1711 with results as follows:-
12th May 1678 - Rebeckah daughter of John Glassan
13th July 1680 - Sarah daughter of John Glasson
10th May 1682 - Robert son of John Glasson
5th August 1688 - Elizabeth daughter of John Glasson
5th April 1691 - William son of John Glasson <====
I believe that the two entries marked (<====) are for the same child thus linking the two sets of baptisms to the one man.
So who was this John Glasson?
As mentioned above there were children baptised at Camborne to 'a' John Glasson in the years up to 1661 and then in 1664 there is an entry for a baptism at Camborne for which no Christian name or gender have been noted. This entry is noted as not appearing in the Bishops Transcripts.
This earlier John is possibly the man who married Elinor Russell although I cannot be certain. But it would seem the later John was not the son of John and Elinor:-
John son of Elinor Glasson, widow, buried 2nd March 1670 Camborne
Elinor Glasson, widow, buried 1st April 1677 Camborne
The later John may be the one baptised at Camborne in 1640 son of William Glasson.
But I am straying from the point which is to try and identify a marriage for John Glasson prior to 1678.
At this point we have only one marriage to consider:-
Jh. Glasson and Katherine his wife were married ye 14th of Jany. 1667 Illogan
However
there is the 'minor problem'
of this entry from the Budock Parish Register:-
Gartheret the daughter of John & Katherin Glazson was baptized the 13th day of June in the yeare of our Lord 1680
That being just one month prior to the baptism of Sarah daughter of John Glasson at Gwinear serves to make things just a little awkward!
And just to compound the problem a little further is that baptisms from around 1666 to about 1687 at Illogan appear to be missing from the register.
I think that should be sufficient for you to try and digest for the time being.
CT