diff --git a/swh/loader/core/loader.py b/swh/loader/core/loader.py
--- a/swh/loader/core/loader.py
+++ b/swh/loader/core/loader.py
@@ -70,6 +70,11 @@
     origin: Origin
     loaded_snapshot_id: Optional[Sha1Git]
 
+    parent_origins: Optional[List[Origin]]
+    """If the given origin is a "forge fork" (ie. created with the "Fork" button
+    of GitHub-like forges), :meth:`build_extrinsic_origin_metadata` sets this to
+    a list of origins it was forked from; closest parent first."""
+
     def __init__(
         self,
         storage: StorageInterface,
@@ -122,6 +127,8 @@
 
         self.save_data_path = save_data_path
 
+        self.parent_origins = None
+
     @classmethod
     def from_config(cls, storage: Dict[str, Any], **config: Any):
         """Instantiate a loader from a configuration dict.
@@ -432,6 +439,8 @@
                 credentials=self.metadata_fetcher_credentials,
             )
             metadata.extend(metadata_fetcher.get_origin_metadata())
+            if self.parent_origins is None:
+                self.parent_origins = metadata_fetcher.get_parent_origins()
 
         return metadata
 
diff --git a/swh/loader/core/metadata_fetchers.py b/swh/loader/core/metadata_fetchers.py
--- a/swh/loader/core/metadata_fetchers.py
+++ b/swh/loader/core/metadata_fetchers.py
@@ -33,6 +33,9 @@
     def get_origin_metadata(self) -> List[RawExtrinsicMetadata]:
         ...
 
+    def get_parent_origins(self) -> List[Origin]:
+        ...
+
 
 @functools.lru_cache()
 def _fetchers() -> List[Type[MetadataFetcherProtocol]]:
diff --git a/swh/loader/core/tests/test_loader.py b/swh/loader/core/tests/test_loader.py
--- a/swh/loader/core/tests/test_loader.py
+++ b/swh/loader/core/tests/test_loader.py
@@ -11,6 +11,7 @@
 import pytest
 
 from swh.loader.core.loader import BaseLoader, DVCSLoader
+from swh.loader.core.metadata_fetchers import MetadataFetcherProtocol
 from swh.loader.exception import NotFound
 from swh.loader.tests import assert_last_visit_matches
 from swh.model.hashutil import hash_to_bytes
@@ -25,6 +26,7 @@
 import swh.storage.exc
 
 ORIGIN = Origin(url="some-url")
+PARENT_ORIGIN = Origin(url="base-origin-url")
 
 METADATA_AUTHORITY = MetadataAuthority(
     type=MetadataAuthorityType.FORGE, url="http://example.org/"
@@ -102,6 +104,31 @@
     def get_origin_metadata(self):
         return [REMD]
 
+    def get_parent_origins(self):
+        return []
+
+
+class DummyMetadataFetcherWithFork:
+    SUPPORTED_LISTERS = {"fake-lister"}
+
+    def __init__(self, origin, credentials, lister_name, lister_instance_name):
+        pass
+
+    def get_origin_metadata(self):
+        return [REMD]
+
+    def get_parent_origins(self):
+        return [PARENT_ORIGIN]
+
+
+def test_types():
+    assert isinstance(
+        DummyMetadataFetcher(None, None, None, None), MetadataFetcherProtocol
+    )
+    assert isinstance(
+        DummyMetadataFetcherWithFork(None, None, None, None), MetadataFetcherProtocol
+    )
+
 
 def test_base_loader(swh_storage):
     loader = DummyBaseLoader(swh_storage)
@@ -138,6 +165,7 @@
     assert swh_storage.raw_extrinsic_metadata_get(
         ORIGIN.swhid(), METADATA_AUTHORITY
     ).results == [REMD]
+    assert loader.parent_origins == []
 
 
 def test_base_loader_with_unknown_lister_name(swh_storage, mocker):
@@ -158,6 +186,32 @@
         swh_storage.raw_extrinsic_metadata_get(ORIGIN.swhid(), METADATA_AUTHORITY)
 
 
+def test_base_loader_forked_origin(swh_storage, mocker):
+    fetcher_cls = MagicMock(wraps=DummyMetadataFetcherWithFork)
+    fetcher_cls.SUPPORTED_LISTERS = DummyMetadataFetcherWithFork.SUPPORTED_LISTERS
+    mocker.patch(
+        "swh.loader.core.metadata_fetchers._fetchers", return_value=[fetcher_cls]
+    )
+
+    loader = DummyBaseLoader(
+        swh_storage, lister_name="fake-lister", lister_instance_name=""
+    )
+    result = loader.load()
+    assert result == {"status": "eventful"}
+
+    fetcher_cls.assert_called_once()
+    fetcher_cls.assert_called_once_with(
+        origin=ORIGIN,
+        credentials={},
+        lister_name="fake-lister",
+        lister_instance_name="",
+    )
+    assert swh_storage.raw_extrinsic_metadata_get(
+        ORIGIN.swhid(), METADATA_AUTHORITY
+    ).results == [REMD]
+    assert loader.parent_origins == [PARENT_ORIGIN]
+
+
 def test_dvcs_loader(swh_storage):
     loader = DummyDVCSLoader(swh_storage)
     result = loader.load()