Is this close family member on AncestryDNA a half sibling?

Question

on ancestry.com i got a "close family" match, with 1,430 centimorgans shared across 58 DNA segments - it says it could be a niece, aunt, or half sibling (range includes 1st cousin, but i have read that's unlikely?) i ruled out grandparent because of age. the person attached a small family tree (only 7 people) there is a couple, gives where they were born and died, then says they had one son (name is private), then he married (shows his spouses parents, also both deceased) and that couple had one daughter. (assuming my match is the last person on tree - female) the tree stops there. only the deceased names are listed - i'm assuming the couple at the top of tree are "grandparents" of my close match (and me?)....and if they had only one son and then they only had one daughter, then she couldn't be my aunt or niece or 1st cousin...so more likely my half sibling?

i just don't know where to go because i have such limited information, no addresses, or dates of immigration, or obituaries attached, this close match hasn't logged on to ancestry in months - another possibility is the tree was never completed.

Answer 1

According to the Centimorgan Calendar, this person is either your:

• half-sibling
• aunt/uncle/niece/nephew
• grandparent/grandchild
• double cousin

I listed the possibilities from what I considered likeliest to least likely, based on what you shared with us.

I'd encourage you to send a message to this person, if you haven't already, even if they haven't logged in. I believe they should receive an email when they get a message.

Are your parents living? Can you ask them for information? Have you tested how well you match any known relatives? How well they match this possible half-sibling?

Answer 2

The amount of matching you show, 1430 cM, falls within the ranges of two possible groups of relationships. By far the most likely, at 93% likelihood, is the set listed by Ellen (half-sibling, aunt/niece, etc). The other group, with about 7% likelihood, includes: half-aunt/-niece, great-aunt/-niece, and first cousin. These probabilities are produced by a Shared cM Project tool.

The tree you found for your match may well not be complete (or even entirely accurate). The person may not have entered all the known siblings in the families, or may not have known about the existence of some siblings or half-siblings. The latter could well be the case -- after all, you apparently were unaware of the existence of this closely-related person. Such a situation may be rather sensitive to your match, so a bit of care in making initial contact with them may be appropriate. You might want to read posts or ask about contacting in a forum with experience in the possible issues, such as the DNA Detectives Facebook group.