Shared 18% DNA

[Cell]

On the point about 2nd cousins.
I have 3 2C matches on MyHeritage at 3-5%, respectively 212.5, 334.7 and 316.4 cM and a fourth on FamilyTree DNA at 206 cM.
I have none on Ancestry where a 339 cM match can only be a half 1C

339 can very easily be a half  first  cousin as too a second cousin, as too a first cousin once removed. I am   not sure where  your statement of 339 is coming in when referring to second cousins or  1st  half cousins? " I have none on Ancestry where a 339 cM match can only be a half 1C" ? ?


I share  over  500cms to both my first  half cousins ( 7% and 8%) and to my full cousins  who have tested , 12% and 15% . With my highest second  cousin I share 363 ( and 5%) all my other second  cousins are 4% and vary between low 200s and high 200s

It is totally  random  the way dna is split outside that parent and child relationship, a few of my cousins , my own  child is almost matching  me with cms ( and he  100%  not double related  to them but I have basically  passed down  the full wack to him on some lines)
Tracy  had said  her known second cousin is 7%  from her mum's  side  ( its her dad's
side that she is querying and  not  her 7% known cousin on her mums side, its  just that I have picked up on that near impossible 7% for a second cousin)
The 7 %  on her mums  side I  personally think is way off   for second  cousins, not 100%  impossible of course but  7% extremely  high for second cousins to be sharing , and just  maybe  Tracey  has mixed up  first  cousin once removed with saying second cousin( ?)

If we go by percentages,  that 7% is very likely  in  the  500s cMs  and it is  a very , very low chance of her known cousin  being  her second  cousin.  I think It's more than likely that's it   her first  cousin once removed and not a second cousin.
 
My mother's  sister thinks I am her second cousin  ,  I haven't the heart to tell  about her terminology as she's  elderly. A few people  in my family  tend  to say   second  cousins when they're referring to their first cousins children , first  cousins once removed .
Kind regards 

[Tracey2016]

I've actually done the DNA through Ancestry, the person who shares 18% DNA
And 1229cM the one that's shares 11%DNA is 763cM. The person who shares 7% DNA is my 1st cousins daughter so she's my 2nd cousin. There was a guy who shared 8% DNA 543cM I contacted him we have a name in common his grandmother and my 2nd great grandmother share the same name he hasn't replied to my email since, he actually has a few shared matches and its the ones at 18% and 11% so fingers crossed he gets back to me

Tracey

[Biggles50]

I've actually done the DNA through Ancestry, the person who shares 18% DNA
And 1229cM the one that's shares 11%DNA is 763cM. The person who shares 7% DNA is my 1st cousins daughter so she's my 2nd cousin. There was a guy who shared 8% DNA 543cM I contacted him we have a name in common his grandmother and my 2nd great grandmother share the same name he hasn't replied to my email since, he actually has a few shared matches and its the ones at 18% and 11% so fingers crossed he gets back to me

Tracey

Your First Cousin’s child is not your Second Cousin, they are your First Cousin Once Removed.

Second Cousin’s share Great Grandparents as their MRCA.

The child you state is a Second Cousin is a Second Cousin with your own Child

[Petros]

I've actually done the DNA through Ancestry, the person who shares 18% DNA
And 1229cM the one that's shares 11%DNA is 763cM. The person who shares 7% DNA is my 1st cousins daughter so she's my 2nd cousin. There was a guy who shared 8% DNA 543cM I contacted him we have a name in common his grandmother and my 2nd great grandmother share the same name he hasn't replied to my email since, he actually has a few shared matches and its the ones at 18% and 11% so fingers crossed he gets back to me

Tracey

1229 and 763 cM are very high on the range that DNApainter gives for 1C and 1C1R. Could there be a second common ancestor? 
The 543 cM match is more in line with the range it gives for 1C1R (102-980) than 2C (41-592)

[LizzieL]

I have quite a wide variation with levels of matches with 1st cousins once removed
546 with a 1st cousin's daughter
412 with my mother's first cousin
248 (4%) with my father's first cousin. (And 128 with her daughter - my second cousin)

I also have a second cousin with whom my match is 406 cm.

He is the grandson of my grandfather's brother. But as that brother was my grandfather's identical twin, the DNA match makes it appear as if he was my half first cousin!

[Tracey2016]

Wow as I said I'm new to all this and learning lots I always thought my cousins child was my 2nd cousin lol every day is a learning day

[Biggles50]

Do you have any siblings?

If you do then they need to take a DNA test.

You may have an NPE and the first thing to do is to validate the near relationships that you have, ie your sibling is a full Brother/Sister and not a half sibling.

If this is not possible then if I was in your position I would make what may be for you is a startling assumption, that my Father is not my Biological Father and then proceed on that assumption until proven otherwise.

[Cell]

I've actually done the DNA through Ancestr The person who shares 7% DNA is my 1st cousins daughter so she's my 2nd cousin.

Tracey

Your  first cousin  daughter is your first cousin once removed.

It's  very rare for second cousins  to be sharing 7%, almost impossible  and I know many  elderly people in my  own family incorrectly  call their 1st cousins once removed  their  second cousins
 Very Kind regards .( ps I meant  to say my mother's  cousin  and not  sister, they grew up together in the same household)